"They loved each other," Farris told CBS Miami affiliate WFOR. "The only time they were violent was when they were drinking."

Indeed, the couple had been drinking and had a shouting argument at a trendy South Beach, Miami nightclub on Jan. 3, the night Sladewski was murdered.

Police have called Klym a person of interest.In a missing person report, Klym told police that bouncers kicked him out of Club Space around 7 a.m. He said he went straight to his hotel and when he woke up and realized Sladewski was missing, he frantically searched for her.

Sladewski's still burning body was found around 14 hours later in a dumpster outside a propane company nearly 100 blocks away. Photo: Paula Sladewski.

Surveillance video from Club Space, released Jan. 8, shows a blonde woman matching Sladewski's description leaving the club at 7:21 a.m. Klym's lawyer, Marc Beginin, is confident the woman on the tape is Sladewski. Police have said they can't be sure.

It's also not clear if she left the club alone or not. Ferris said club employees told her she left arm-in-arm with a man who wasn't her boyfriend. Beginin claims the surveillance tape shows Sladewski was followed out of the club.

The tape "shows another gentleman following her out of the night club. That is the person police should be looking for," Beginin told WFOR. But it's not at all clear that the blonde on the tape is Sladewski or that the person leaving the club after her is following her.

According to Sladewski's stepfather, Richard Watkins, the pair had a violent relationship and he had begged them to separate.

Last year, Sladewski was arrested for breaking a bottle over Klym's head, according to a police report and Watkins' description of the attack. Charges were later dropped.

In December, Klym was arrested for breaking Sladewski's nose and part of her cheek, according to a Michigan police report. That case has not been adjudicated.

Beginin has said regardless of their turbulent past, Klym is totally innocent and did all he could as soon as he realized Sladewski was missing. Beginin told CBS News' Crimesider that Klym called morgues, Sladewski's family, and a private investigator and handed out fliers before filing a missing person report around 14 hours after he said he last saw her. He believes surveillance video from his hotel, if it exists, will vindicate his story.

Sladewski was an aspiring model who appeared in a 2003 Playboy talent search video. Recently, she worked as an exotic dancer to make money. Klym listed his occupation as a laborer on the missing person report. The couple lived in both Michigan and California.

As for Farris, she says she will not rest until her sister's killer is brought to justice.

"I'm the voice for her," she told WFOR. "She can't speak. Only God knows who the killer is and I want the killer to pay for what he did."